Non-aqueous coating material which is thermally hardenable or hardenable in a thermal manner and by means of actinic radiation, method for the production and use thereof

ABSTRACT

A nonaqueous coating material curable thermally or thermally and with actinic radiation, comprising  
     (A) a hydroxyl-containing binder component comprising  
     (A1) at least one hydroxyl-containing polyester and  
     (A2) at least one hydroxyl-containing (meth)acrylate copolymer prepared at least partly in the presence of the polyester (A1)  
     (B) at least one crosslinking component comprising at least one polyisocyanate, and  
     (C) at least one low molecular mass and/or oligomeric, essentially unbranched, hydrophobic polyester having at least two hydroxyl groups in the molecule, an OH number of from 56 to 500 mg KOH/g, an acid number &lt;10 mg KOH/g, and a number-average molecular weight Mn of from 300 to 2000 daltons;  
     process for its preparation, and its use.

[0001] The present invention relates to a novel nonaqueous coatingmaterial curable thermally or thermally and with actinic radiation. Thepresent invention also relates to a novel process for preparing acoating material, especially the novel coating material. The presentinvention additionally relates to the use of the novel coating materialto produce coatings, especially automotive OEM finishes, commercialvehicle finishes, and automotive refinishes.

[0002] Nonaqueous coating materials curable thermally or thermally andwith actinic radiation and comprising

[0003] (A) a hydroxyl-containing binder component comprising

[0004] (A1) at least one hydroxyl-containing polyester and

[0005] (A2) at least one hydroxyl-containing (meth)acrylate copolymerprepared at least partly in the presence of the polyester (A1) and

[0006] (B) at least one crosslinking component comprising at least onepolyisocyanate

[0007] are known from German Patent Application DE 40 24 204 A1 or fromInternational Patent Application WO 96/26969.

[0008] The coating materials known from German Patent Application DE 4024 204 A1 have a long pot life despite which they may be cured veryrapidly at room temperature or slightly elevated temperature. Thecoatings produced from them have very good mechanical properties andgood gloss retention, crack resistance, fullness, and evenness.

[0009] Furthermore, the coating materials known from InternationalPatent Application WO 96/26969, and the coatings produced from them,respectively, have improved masking resistance, solvent resistance, andsurface hardness.

[0010] The known coating materials have the disadvantage that the amountof volatile organic compounds emitted in the course of their applicationand curing exceeds the current statutory provisions. In other words, thevolatile organic compounds (VOC) content of the known coating materialsis too high and surpasses the presently valid limits.

[0011] Since, however, the known coating materials and the coatingsproduced from them, as indicated above, possess outstanding performanceproperties, it would be highly desirable to be able to continue to usethem. To do so, however, would require the VOC to be reduced below thestatutory limits without impairment to the profile of properties.Increasing the solids content and/or adding water, however, leads to anunacceptable impairment of the performance properties of coatingmaterial and coating.

[0012] German Patent Application DE 199 14 899.6, unpublished at thepriority date of the present specification, describes an aqueous coatingmaterial comprising at least three components, viz. a component (I)comprising at least one oligomeric or polymeric resin containingfunctional groups which react with isocyanate groups, as binder (A), acomponent (II) comprising at least one polyisocyanate, as crosslinkingagent (B), and a component (III) comprising water, and component (I)and/or (III) comprising at least one essentially unbranched hydrophobicpolyester (C) which is of low molecular mass and/or is oligomeric, hasat least two hydroxyl groups in the molecule and has an OH number offrom 56 to 500 mg KOH/g, an acid number <10 mg KOH/g, and anumber-average molecular weight Mn of from 450 to 2000 daltons.

[0013] It is an object of the present invention to provide a newnonaqueous coating material, curable thermally or thermally and withactinic radiation, which is obtainable by simple material variation ofknown coating materials, has a long pot life, and nevertheless curesrapidly at room temperature or slightly elevated temperature to givecoatings possessing very good mechanical properties and also very goodgloss retention, crack resistance, fullness and evenness, maskingresistance, solvent resistance and surface hardness, the VOCs fallingbelow the prescribed limits without detriment to the advantageousprofile of properties of coating material and coating.

[0014] Accordingly we have found the novel nonaqueous coating materialcurable thermally or thermally and with actinic radiation and comprising

[0015] (A) a hydroxyl-containing binder component comprising

[0016] (A1) at least one hydroxyl-containing polyester and

[0017] (A2) at least one hydroxyl-containing (meth)acrylate copolymerprepared at least partly in the presence of the polyester (A1),

[0018] (B) at least one crosslinking component comprising at least onepolyisocyanate, and

[0019] (C) at least one low molecular mass and/or oligomeric,essentially unbranched, hydrophobic polyester having at least twohydroxyl groups in the molecule, an OH number of from 56 to 500 mgKOH/g, an acid number <10 mg KOH/g, and a number-average molecularweight Mn of from 300 to 2000 daltons.

[0020] In the text below, the novel nonaqueous coating material curablethermally or thermally and with actinic radiation is referred to as the“coating material of the invention”.

[0021] Further subject matter of the invention will emerge from thedescription.

[0022] In the light of the prior art it was surprising and unforeseeablefor the skilled worker that the object on which the present invention isbased could be achieved through the use of the polyesters (C), since onthe contrary it was to have been expected that the addition of polyester(C) to the known coating materials would alter their profile ofproperties and also the profile of properties of the coatings producedfrom them in an unforeseeable and deleterious way. However, theinventive addition of the polyesters (C) solved the problems describedabove without the need to make any fundamental alteration to thematerial composition of the known coating materials.

[0023] The coating material of the invention is curable thermally orthermally and with actinic radiation. It is thermally externallycrosslinking.

[0024] In the context of the present invention, binders are referred toas externally crosslinking if they comprise one kind of complementaryreactive functional groups (in the present case hydroxyl groups) whichare able to undergo crosslinking reactions with another kind ofcomplementary reactive functional groups (in the present case isocyanategroups) in a curing or crosslinking agent. For further details,reference is made to Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, Stuttgart, New York, 1998, “Curing”, pages 274 to 276,especially bottom of page 275.

[0025] In the context of the present invention, actinic radiation iselectromagnetic radiation such as near infrared (NIR), visible light, UVradiation or X-rays, especially UV radiation, and corpuscular radiationsuch as electron beams.

[0026] The joint use of thermal curing and actinic radiation curing isreferred to by those in the art as dual cure.

[0027] In the text below, the individual constituents of the coatingmaterial of the invention are elucidated further.

[0028] The coating material of the invention comprises ahydroxyl-containing binder component (A) comprising

[0029] (A1) from 20 to 60% by weight, preferably from 30 to 50% byweight, of at least one polyester, and

[0030] (A2) from 40 to 80% by weight, preferably from 50 to 70% byweight, of at least one hydroxyl-containing (meth)acrylate copolymerprepared at least partly in the presence of the polyester (A1).

[0031] The binder component (A) preferably has a hydroxyl number of from80 to 150, with particular preference from 85 to 105 mg KOH/g and anacid number of from 0.1 to 10, preferably from 4 to 8 mg KOH/g.

[0032] It is essential to the invention that the polyester (A1) has anOH number of from 90 to 130, preferably from 90 to 110 mg KOH/g, an acidnumber of less than 10 mg KOH/g, preferably from 1 to 8 mg KOH/g, anumber-average molecular weight of from 1300 to 3500, preferably from1350 to 2000, and a polydispersity of from 5 to 50, preferably from 5 to10. The polydispersity is defined as the ratio of weight-averagemolecular weight to number-average molecular weight. The molecularweights are in each case determined by gel permeation chromatographyagainst polystyrene standard.

[0033] The polyesters (A1) are preferably obtainable by reacting

[0034] p1) polycarboxylic acids or their esterifiable derivatives, aloneor together with monocarboxylic acids,

[0035] p2) polyols, alone or together with monools,

[0036] p3) if desired, further, modifying components, and

[0037] p4) if desired, a component reactive with the reaction product of(p1), (p2) and, if used, (p3).

[0038] Examples of polycarboxylic acids which may be used as component(p1) include aromatic, aliphatic and cycloaliphatic polycarboxylicacids. As component (p1) it is preferred to use aromatic and/oraliphatic polycarboxylic acids.

[0039] Examples of suitable polycarboxylic acids are phthalic acid,isophthalic acid, terephthalic acid, halophthalic acids, such astetrachloro- and tetrabromophthalic acid, adipic acid, glutaric acid,azelaic acid, sebacic acid, fumaric acid, maleic acid, trimellitic acid,pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid,1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid,1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid,endomethylenetetrahydrophthalic acid, tricyclodecanedicarboxylic acid,endoethylenehexahydrophthalic acid, camphoric acid,cyclohexanetetracarboxylic acid, cyclobutanetetracarboxylic acid, etc.The cycloaliphatic polycarboxylic acids may be used either in their cisor in their trans form and also as a mixture of both forms. Alsosuitable are the esterifiable derivatives of the abovementionedpolycarboxylic acids, such as their monoesters or polyesters withaliphatic alcohols having 1 to 4 carbon atoms or hydroxy alcohols having1 to 4 carbon atoms. A further possibility is to use the anhydrides ofthe abovementioned acids, where they exist.

[0040] If desired, together with the polycarboxylic acids (p1) it isalso possible to use monocarboxylic acids (p1), such as benzoic acid,tert-butylbenzoic acid, lauric acid, isononanoic acid and fatty acids ofnaturally occurring oils, for example. Preferably, isononanoic acid isused as monocarboxylic acid.

[0041] Suitable alcohol components (p2) for preparing the polyester oralkyd resin (A1) are polyhydric alcohols, such as ethylene glycol,propanediols, butanediols, hexanediols, neopentyl glycol, diethyleneglycol, cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol,ethylbutylpropanediol, ditrimethylolpropane, trimethylolethane,trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol,trishydroxyethyl isocyanate, polyethylene glycol, polypropylene glycol,alone or together with monohydric alcohols (p2), such as butanol,octanol, lauryl alcohol, ethoxylated and/or propoxylated phenols, forexample.

[0042] Particularly suitable components (p3) for preparing thepolyesters (A1) are compounds having a group which is reactive towardthe functional groups of the polyester, with the exception of thecompounds specified as component (p4). As modifying component (p3) it ispreferred to use polyisocyanates and/or diepoxide compounds, along withmonoisocyanates and/or monoepoxide compounds if desired. Suitablecompounds (p3) are described, for example, in DE 40 24 204 A1 on page 4lines 4 to 9.

[0043] Suitable components (p4) for preparing the polyesters or alkydresins (A1) are compounds which in addition to a group which is reactivetoward the functional groups of the polyester (A1) also have a tertiaryamino group, examples being monoisocyanates containing at least onetertiary amino group or mercapto compounds containing at least onetertiary amino group. For details, reference is made to DE 40 24 204 A1,page 4 lines 10 to 49.

[0044] The polyesters (A1) are prepared in accordance with the knownmethods of esterification [cf. various standard works, such as, forexample:

[0045] 1. Temple C. Patton, Alkyd Resin Technology, IntersciencePublishers John Wiley & Sons, New York, London 1962;

[0046] 2. Dr. Johannes Scheiber, Chemie und Technologie der künstlichenHarze, Wissenschaftliche Verlags-gesellschaft mbH, Stuttgart, 1943;

[0047] 3. Hans Wagner+Hans-Friedrich Sarx, Lackkunstharze, 4th Edition,Carl Hanser Verlag, Munich, 1959;

[0048] 4. Ullmanns Encyklopädie der technischen Chemie, Volume 14, pages80 to 106 (1963)].

[0049] The reaction takes place usually at temperatures between 180 and280° C., in the presence if desired of an appropriate esterificationcatalyst, such as lithium octoate, dibutyltin oxide, dibutyltindilaurate, para-toluenesulfonic acid and the like, for example.

[0050] Normally, the preparation of the polyesters (A1) is conducted inthe presence of small amounts of an appropriate solvent as entrainer.Examples of entrainers used are aromatic hydrocarbons, such asespecially xylene and (cyclo)aliphatic hydrocarbons, e.g., cyclohexane.

[0051] The (meth)acrylate copolymers used as component (A2) in thecoating materials of the invention have OH numbers of from 50 to 150 mgKOH/g, preferably from 70 to 105 mg KOH/g, and acid numbers of from 0 to10 mg KOH/g, preferably from 0 to 8 mg KOH/g, the OH numbers and acidnumbers each being calculated without taking into account the polyestercomponent (A1). The number-average molecular weights of the(meth)acrylate copolymers (A2) prepared in the presence of thepolyesters (A1) are usually between 1500 and 5000, preferably between2000 and 4000, in each case measured by GPC polystyrene standard.

[0052] It is essential to the invention that the (meth)acrylatecopolymer (A2) has been prepared at least partly in the presence of apolyester resin (A1). Advantageously, at least 30% by weight and,preferably, at least 40% by weight of the component (A2) is prepared inthe presence of the component (A1).

[0053] Any remaining amount of the component (A2) is added subsequentlyto the binder solution and/or to the coating material. It is possiblefor this already polymerized (meth)acrylate copolymer (A2) to have thesame monomer composition as the (meth)acrylate copolymer (A2)synthesized in the presence of the polycondensation resin (A1).Alternatively, it is possible to add a hydroxyl-containing polyadditionresin and/or polycondensation resin having a different monomercomposition. A further possibility is to add a mixture of differentpolyaddition resins (A2) and/or polycondensation resins (A1), one resinpossibly having the same monomer composition as the polyaddition resin(A2) synthesized in the presence of the polycondensation resin (A1).

[0054] It is further essential to the invention that the (meth)acrylatecopolymer (A2) comprises one or more copolymerized monomer componentsselected from the group of the hydroxyalkyl esters of acrylic acid,methacrylic acid or another alpha,beta-ethylenically unsaturatedcarboxylic acid which are derived from alkylene glycols that areesterified with the acids, or are obtainable by reacting the acids withalkylene oxides; especially hydroxyalkyl esters of acrylic acid,methacrylic acid or ethacrylic acid in which the hydroxyalkyl groupcontains up to 20 carbon atoms, such as 2-hydroxyethyl, 2-hydroxypropyl,3-hydroxypropyl, 3-hydroxybutyl or 4-hydroxybutyl acrylate,methacrylate, ethacrylate or crotonate;1,4-bis(hydroxymethyl)cyclohexane,octahydro-4,7-methano-1H-indene-dimethanol or methylpropanediolmonoacrylate, monomethacrylate, monoethacrylate or monocrotonate;reaction products of cyclic esters, such as ε-caprolactone, for example,and these hydroxyalkyl esters; reaction products of acrylic acid and/ormethacrylic acid with the glycidyl ester of a carboxylic acid having atertiary α carbon atom (these glycidyl esters of carboxylic acidsbranched on the α carbon atom and containing 11 to 13 carbon atoms(Versatic® acid) are obtainable, commercially, for example, under thename Cardura® from Shell; the reaction of the acrylic and/or methacrylicacid with the glycidyl ester may take place before, during or after thepolymerization).

[0055] Preferably, the acrylate resin (A2) comprises one or moremonomers selected from the group consisting of 4-hydroxy-n-butylacrylate, 4-hydroxy-n-butyl methacrylate, 3-hydroxy-n-butyl acrylateand/or 3-hydroxy-n-butyl methacrylate, together if desired withhydroxyethyl methacrylate.

[0056] The (meth)acrylate copolymers (A2) used in accordance with theinvention may be prepared by well-known polymerization techniques.Polymerization techniques for preparing (meth)acrylate copolymers arewidely known and much described (cf., e.g., Houben-Weyl, Methoden derorganischen Chemie, 4th Edition, Volume 14/1, pages 24 to 255 (1961) orGerman Patent Application DE 40 24 204 A1, page 4 line 66 to page 7 line38).

[0057] The (meth)acrylate copolymers (A2) used in accordance with theinvention are prepared preferably with the aid of the solutionpolymerization technique. In this technique an organic solvent orsolvent mixture is usually introduced as an initial charge together withthe polyester (A1) and heated to boiling. The monomer mixture to bepolymerized, along with one or more polymerization initiators, is thenadded continuously to this mixture of organic solvent or solvent mixtureand polyester resin (A1). The polymerization takes place at temperaturesbetween 100 and 160° C., preferably between 130 and 150° C.

[0058] The polymerization is preferably conducted in at least onehigh-boiling organic solvent (E) which is inert toward the monomersused. Examples of suitable solvents are aromatics with fairly highdegrees of substitution, such as Solvent Naphtha®, heavy petroleumspirit, various Solvesso® grades, various Shellsol® grades and Deasol®,and also relatively high-boiling aliphatic and cycloaliphatichydrocarbons, such as various white spirits, mineral turpentine oil,tetralin and decalin, and also various esters, such as ethyl glycolacetate, butyl glycol acetate, ethyl diglycol acetate, and the like.

[0059] As polymerization initiators it is preferred to use initiatorswhich form free radicals. The type and amount of initiator are normallychosen so that the supply of free radicals at polymerization temperatureis as constant as possible during the feed phase.

[0060] Examples of initiators which may be used include the following:di-tert-butyl peroxide, tert-butyl hydroperoxide, tert-butylperoxybenzoate, tert-butyl peroxypivalate, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-butyl peroxy-2-ethylhexanoate,dicumyl peroxide, cumyl hydroperoxide, tert-amyl peroxybenzoate,tert-amyl peroxy-2-ethylhexanoate, diacyl peroxides, such as diacetylperoxide, for example, peroxyketals, 2,2-di(tert-amylperoxy)propane,ethyl 3,3-di(tert-amylperoxy)butyrate, and thermally labile highlysubstituted ethane derivatives, based for example on silyl-substitutedethane derivatives and on benzpinacol. Furthermore, it is also possibleto use aliphatic azo compounds, such as azoisovaleronitrile andazobiscyclohexanenitrile, for example.

[0061] Initiators containing tert-butyl groups, such as di-tert-butylperoxide, tert-butyl hydroperoxide, 2,2-di-tert-butylperoxybutane and1,3-bis(tert-butylperoxyisopropyl)benzene, for example, are used inparticular since they promote grafting of the (meth)acrylate copolymer(A2) onto the polyester (A1).

[0062] The amount of initiator is from 0.1 to 8% by weight in themajority of cases, based on the amount of monomer to be processed, butmay also be higher if desired. The initiator, dissolved in a portion ofthe solvent used for the polymerization, is metered in gradually duringthe polymerization reaction. The initiator feed preferably lasts forabout 0.5 to 2 hours longer than the monomer feed, in order to ensure agood effect during the postpolymerization phase. In another preferredpreparation variant, the initiator feed is commenced about 15 minutesbefore the addition of the monomers, in order to provide a large supplyof free radicals at the beginning of the polymerization. Where thedecomposition rate of the initiators used is low under the prevailingreaction conditions, it is also possible to include the initiator in theinitial charge.

[0063] The polymerization conditions (reaction temperature, feed time ofthe monomer mixture, amount and nature of the organic solvents andpolymerization initiators, possible use of molecular weight regulators,such as mercaptans, thioglycolic esters and chlorinated hydrocarbons,for example) are chosen so that the (meth)acrylate copolymers (A2) usedin accordance with the invention have the desired molecular weight.

[0064] The acid number of the (meth)acrylate copolymers (A2) used inaccordance with the invention may be adjusted by the skilled workerusing appropriate amounts of carboxyl-containing monomers. Similarcomments apply to the adjustment of the hydroxyl number: it may becontrolled by way of the amount of hydroxyl-containing monomers used.

[0065] It is preferred as component (A2) to use hydroxyl-containing(meth)acrylate copolymers obtainable by polymerizing

[0066] (a) from 5 to 95% by weight, preferably from 45 to 85% by weight,of one or more monomers selected from the group of the above-describedhydroxyl-containing, ethylenically unsaturated, copolymerizablemonomers;

[0067] (b) from 5 to 95% by weight, preferably from 15 to 55% by weight,of an aliphatic and/or cycloaliphatic ester of methacrylic and/oracrylic acid other than (a), or of a mixture of such monomers;

[0068] (c) from 0 to 30% by weight, preferably from 5 to 15% by weight,of a copolymerizable vinyl ester other than (a) and (b), or of a mixtureof such monomers;

[0069] (d) from 0 to 85% by weight, preferably from 15 to 60% by weight,of a vinylaromatic hydrocarbon other than (a), (b) and (c), or of amixture of such monomers, and

[0070] (e) from 0 to 10% by weight, preferably from 0 to 8% by weight,of a further ethylenically unsaturated monomer other than (a), (b), (c)and (d), or of a mixture of such monomers,

[0071] at least partly in the presence of component (A1) to give the(meth)acrylate copolymer (A2), the sum of the weight fractions of themonomers (a) to (e) being in each case 100% by weight.

[0072] As the monomer (b) it is possible in principle to use anyaliphatic or cycloaliphatic esters of acrylic acid or of methacrylicacid, other than (a), or a mixture of such monomers. Examples includealiphatic esters of acrylic acid and of methacrylic acid, such asmethyl, ethyl, propyl, n-butyl, isobutyl, tert-butyl, n-hexyl,2-ethylhexyl, stearyl and lauryl acrylate and also the correspondingmethacrylates, for example, and cycloaliphatic esters of (meth)acrylicacid, such as furfuryl, cyclohexyl, isobornyl, and t-butylcyclohexylacrylate and methacrylate, for example.

[0073] Monomers (c) used are vinyl esters of monocarboxylic acids. It ispreferred to use vinyl esters of α-branched monocarboxylic acids having5 to 15 carbon atoms per molecule. The branched monocarboxylic acids maybe obtained by reacting formic acid or carbon monoxide and water witholefins in the presence of a liquid, strongly acidic catalyst; theolefins may be cracking products of paraffinic hydrocarbons, such asmineral oil fractions, and may comprise both branched and straight-chainacyclic and/or cycloaliphatic olefins. The reaction of such olefins withformic acid or with carbon monoxide and water produces a mixture ofcarboxylic acids in which the carboxyl groups are located predominantlyon a quaternary carbon atom. Other olefinic starting materials are, forexample, propylene trimer, propylene tetramer, and diisobutylene. Thevinyl esters may also be prepared in the manner known per se from theacids, for example, by reacting the acids with acetylene.

[0074] Particular preference is given, owing to their readyavailability, to vinyl esters of saturated aliphatic monocarboxylicacids with 9-11 carbon atoms which are branched on the α carbon atom.

[0075] Also particularly preferred is the vinyl ester ofp-tert-butylbenzoic acid. Examples of further suitable vinyl esters arevinyl acetate and vinyl propionate.

[0076] Monomers (d) used are vinylaromatic hydrocarbons, such asstyrene, α-alkylstyrenes, such as α-methylstyrenes, chlorostyrenes, o-,m- and p-methylstyrene, 2,5-dimethylstyrene, p-methoxystyrene,p-tert-butylstyrene, p-dimethylaminostyrene, p-acetamidostyrene, andvinyltoluene, preference being given to the use of vinyltoluenes, andespecially styrene.

[0077] As component (e) it is possible in principle to use anyethylenically unsaturated monomer other than (a), (b), (c) and (d), or amixture of such monomers. Examples of monomers which may be used ascomponent (e) include the following: carboxyl-containing monomers, suchas acrylic and/or methacrylic acid, for example; amides of acrylic acidand methacrylic acid, such as methacrylamide and acrylamide, forexample; nitriles of methacrylic acid and acrylic acid; and vinyl ethersand vinyl esters.

[0078] The further essential constituent of the coating material of theinvention is at least one crosslinking component (B). It comprises orconsists of at least one polyisocyanate.

[0079] Examples of suitable polyisocyanates (B) are organicpolyisocyanates containing free isocyanate groups attached to aliphatic,cycloaliphatic, araliphatic and/or aromatic moieties. Preference isgiven to polyisocyanates having from 2 to 5 isocyanate groups permolecule. If desired, small amounts of organic solvents, preferably from1 to 25% by weight, based on the polyisocyanate itself, may be added tothe polyisocyanates in order to make it easier to incorporate them.Suitable solvent additives for the polyisocyanates are, for example,ethoxyethyl propionate, butyl acetate and the like.

[0080] Examples of suitable polyisocyanates (B) are described, forexample, in “Methoden der organischen Chemie”, Houben-Weyl, Volume 14/2,4th Edition, Georg Thieme Verlag, Stuttgart 1963, pages 61 to 70, and byW. Siefken, Liebigs Ann. Chem. 562, 75 to 136.

[0081] Suitable examples include 1,2-ethylene diisocyanate,1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-and 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecanediisocyanate, ω,ω′-diisocyanatodipropyl ether, cyclobutane1,3-diisocyanate, cyclohexane 1,3- and 1,4-diisocyanate, 2,2- and2,6-diisocyanato-1-methylcyclohexane,3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (“isophoronediisocyanate”), 2,5- and3,5-bis(isocyanatomethyl)-8-methyl-1,4-methanodecahydronaphthalene,1,5-, 2,5-, 1,6- and2,6-bis(isocyanatomethyl)-4,7-methanohexahydroindane, 1,5-, 2,5-, 1,6-and 2,6-bis(isocyanato)-4,7-methanohexahydroindane, dicyclohexyl 2,4′-and 4,4′-diisocyanate, 2,4- and 2,6-hexahydrotolylene diisocyanate,perhydro-2,4′- and -4,4′-diphenylmethane diisocyanate,ω,ω′-diisocyanato-1,4-diethylbenzene, 1,3- and 1,4-phenylenediisocyanate, 4,4′-diisocyanatobiphenyl,4,4′-diisocyanato-3,3′-dichlorobiphenyl,4,4′-diisocyanato-3,3′-dimethoxybiphenyl,4,4′-diisocyanato-3,3′-dimethylbiphenyl,4,4′-diisocyanato-3,3′-diphenylbiphenyl, 2,4′- and4,4′-diisocyanatodiphenylmethane, naphthylene 1,5-diisocyanate, tolylenediisocyanates, such as 2,4- and 2,6-tolylene diisocyanate,N,N′-(4,4′-dimethyl-3,3′-diisocyanatodiphenyl)uretdione, m-xylylenediisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylenediisocyanate, and also trilsocyanates, such as2,4,4′-triisocyanatodiphenyl ether and4,4′,4″-triisocyanatotriphenylmethane. It is preferred, alone or incombination with the abovementioned polyisocyanates, to usepolyisocyanates containing isocyanurate groups, biuret groups,allophanate groups, uretdione groups, iminooxadiazinedione groups,urethane groups and/or urea groups. Polyisocyanates containing urethanegroups, for example, are obtained by reacting some of the isocyanategroups with polyols, such as trimethylolpropane and glycerol, forexample.

[0082] Preference is given to the use of aliphatic or cycloaliphaticpolyisocyanates (B), especially hexamethylene diisocyanate, dimerizedand trimerized hexamethylene diisocyanate, isophorone diisocyanate,dicyclohexylmethane 2,4′-diisocyanate or dicyclohexylmethane4,4′-diisocyanate, or mixtures of these polyisocyanates. Very particularpreference is given to using mixtures of polyisocyanates based onhexamethylene diisocyanate and containing uretdione and/or isocyanurategroups and/or allophanate groups, as formed by catalytic oligomerizationof hexamethylene diisocyanate using appropriate catalysts. Thecrosslinking component (B) may otherwise comprise any desired mixturesof the exemplified polyisocyanates (B).

[0083] The amount of the polyisocyanates (B) used is chosen so that theratio of the isocyanate groups to the hydroxyl groups of the bindercomponent (A) and of the hydroxyl groups of the hydrophobic polyesters(C) described below is in the range from 1:3 to 3:1. Preferably, thecoating materials of the invention contain from 15 to 70% by weight ofthe polyester-modified (meth)acrylate copolymer (A1/A2), from 0 to 30%by weight of the further binder component (A1) and/or (A2), and from 7to 50% by weight of the polyisocyanates (B), based in each case on thesolids of the coating material of the invention.

[0084] In the context of the present invention, “solids” hereinbelowdenotes that fraction of the coating material of the invention formed bythe coating after curing.

[0085] The constituent of the coating material of the invention that isessential to the invention is at least one hydrophobic polyester (C).

[0086] The hydrophobic polyesters (C) may be compounds of low molecularmass, having a molecular weight of in particular from 300 to 700daltons. In accordance with the invention, advantageous hydrophobicpolyesters (C) of low molecular mass are those which are not volatileunder the conditions of preparation and application of the coatingmaterial of the invention.

[0087] However, the hydrophobic polyesters (C) may also be oligomericcompounds, having a number-average molecular weight Mn of from 400 to2000, preferably from 450 to 1500, with particular preference from 600to 1200, and in particular from 650 to <1000.

[0088] The low molecular mass and the oligomeric hydrophobic polyesters(C) may be used individually or as a mixture.

[0089] The polyesters (C) are hydrophobic. In the context of the presentinvention, and in accordance with DIN EN ISO 862:1995-10, the term“hydrophobic” denotes the constitutional property of a molecule tobehave exophilically with respect to water; in other words, it displaysthe tendency not to penetrate into water or to depart the aqueous phase.

[0090] The hydrophobic polyesters (C) are essentially unbranched, i.e.,in contrast to the dendrimers described below as reactive diluents,their molecules are essentially linear.

[0091] The hydrophobic polyesters (C) have at least 2, preferably 4, andespecially 3 hydroxyl groups in the molecule. Advantageously, the numberof hydroxyl groups is chosen so as to give an OH number of from 56 to500, preferably from 70 to 450, with particular preference from 80 to350, and in particular from 100 to 300 mg KOH/g.

[0092] The hydrophobic polyesters (C) are essentially free from acidgroups, i.e., they have an acid number of <3 mg KOH/g.

[0093] Preferred low molecular mass hydrophobic polyesters (C) have thegeneral formula I

[R¹—CH(OH)—CH₂—OOC—]₂R  (I)

[0094] where

[0095] R=substituted or unsubstituted divalent C₁ to C₂₀ alkanediyl, C₂to C₂₀ alkenediyl, C₄ to C₂₀ cycloalkanediyl or cycloalkenediyl, C₆ toC₁₂ arylidene or divalent C₆ to C₂₀ arylalkyl, arylalkenyl,arylcycloalkyl or arylcycloalkenyl radical; or substituted orunsubstituted divalent aliphatic, cycloaliphatic, acyclic or cyclicolefinically unsaturated, aromatic, aliphatic-aromatic,cycloaliphatic-aromatic, acyclic unsaturated aromatic or cyclicunsaturated aromatic radical containing at least one carboxylic estergroup;

[0096] R¹=hydrogen atom or monovalent substituted or unsubstituted C₁ toC₂₀ alkyl, C₂ to C₂₀ alkenyl, C₄ to C₁₂ cycloalkyl or cycloalkenyl, C₆to C₁₂ aryl or C₆ to C₂₀ arylalkyl, arylalkenyl, arylcycloalkyl,arylcycloalkenyl, alkylaryl, alkenylaryl, cycloalkylaryl,cycloalkenylaryl, alkylcycloalkyl, alkylcycloalkenyl, alkenylcycloalkyl,alkenylcycloalkenyl, cycloalkylalkyl, cycloalkenylalkyl,cycloalkylalkenyl or cycloalkenylalkenyl radical.

[0097] Examples of suitable C₁ to C₂₀ alkanediyl radicals R aremethylene, ethylene, propane-1,3-diyl, tetramethylene, pentamethylene,hexamethylene, heptamethylene, dodecane-1,12-diyl orhexadecane-1,16-diyl.

[0098] Examples of suitable C₂ to C₂₀ alkenediyl radicals R areethene-1,2-diyl, propene-1,3-diyl or dodecene-1,12-diyl.

[0099] Examples of suitable C₄ to C₂₀ cycloalkanediyl radicals R arecyclopentane-1,2- or -1,3-diyl or cyclohexane-1,2-, -1,3- or -1,4-diyl.

[0100] Examples of suitable C₄ to C₂₀ cycloalkenediyl radicals R arecyclopentene-1,2- or -1,3-diyl or cyclohexene-1,2-, -1,3- or -1,4-diyl.

[0101] Examples of suitable C₆ to C₁₂ arylidene radicals R are 1,2-,1,3- or 1,4-phenylene or 1,3-, 1,4- or 2,5-naphthylene or1,4′-biphenylene.

[0102] Examples of suitable divalent C₆ to C₂₀ arylalkyl radicals R are

[0103] Examples of suitable divalent arylalkenyl radicals are

[0104] Examples of suitable divalent arylcycloalkyl radicals R are

[0105] Examples of suitable divalent arylcycloalkenyl radicals R are

[0106] Examples of suitable divalent aliphatic, cycloaliphatic, acyclicor cyclic olefinically unsaturated, aromatic, aliphatic-aromatic,cycloaliphatic-aromatic, acyclic unsaturated aromatic or cyclicunsaturated aromatic radicals R containing at least one carboxylic estergroup are

[0107] Suitable substituents of these radicals R are all organicfunctional groups which are essentially inert, i.e., do not undergo anyreactions with the crosslinking agents (B). Examples of suitable inertorganic radicals are halogen atoms, nitro groups, nitrile groups, andalkoxy groups. Further suitable substituents include functional groupswhich are able to undergo crosslinking reactions with the crosslinkingagents (B), such as amino, thiol or hydroxyl groups, of which thehydroxyl groups are particularly advantageous in accordance with theinvention and are therefore used with particular preference.

[0108] In accordance with the invention it is especially advantageous ifthe radical R contains at least one hydroxyl group as substituent.

[0109] Examples of suitable, unsubstituted or substituted C₁ to C₁₀alkyl radicals R¹ for use in accordance with the invention are methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl or decylradicals.

[0110] Examples of suitable substituted or unsubstituted C₂ to C₂₀alkenyl, C₄ to C₁₂ cycloalkyl or cycloalkenyl, C₆ to C₁₂ aryl or C₆ toC₂₀ arylalkyl, arylalkenyl, arylcycloalkyl, arylcycloalkenyl, alkylaryl,alkenylaryl, cycloalkylaryl, cycloalkenylaryl, alkylcycloalkyl,alkylcycloalkenyl, alkenylcycloalkyl, alkenylcycloalkenyl,cycloalkylalkyl, cycloalkenylalkyl, cycloalkylalkenyl orcycloalkenylalkenyl radicals R¹ are

[0111] In accordance with the invention it is of advantage if theradical R¹ is substituted.

[0112] Examples of suitable substituents of the radical R¹ are —F, —Cl,—Br, —I, —CN, —NO₂, —OH, —OR², —SH, —SR₂, —NH₂, —NHR², —N(NR²)₂ and/or—OOC—R², where R² is as defined for R¹ with the exception of thehydrogen atom.

[0113] Examples of suitable radicals R² of this kind are those describedabove in the context of the radicals R¹.

[0114] Further examples of suitable radicals R² are branched C₄ to C₁₂alkyl radicals, especially 1,1-dimethylethan-1-yl, -propan-1-yl,-butan-1-yl, -pentan-1-yl, -hexan-1-yl or -heptan-1-yl, which are ofadvantage in accordance with the invention and are therefore used withpreference.

[0115] In accordance with the invention it is of particular advantage ifthe radical R¹ is a monosubstituted methyl group.

[0116] Furthermore, it is of particular advantage in accordance with theinvention if the radical R¹, especially the methyl group, is substitutedby —OOC—R².

[0117] The preparation of the hydrophobic polyesters (C) has no specialfeatures in terms of its method but instead takes place by means of thecustomary and known methods of preparing low molecular mass andoligomeric polyesters. Examples of suitable methods are those describedabove in the context of the preparation of the polyester (A1).

[0118] Advantageous low molecular mass hydrophobic polyesters (C) may beprepared in particular by reacting hydroxydicarboxylic acids withepoxides.

[0119] Examples of suitable hydroxydicarboxylic acids are tartronicacid, malic acid, and tartaric acid.

[0120] Examples of suitable epoxides, especially those containingglycidyl groups, are ethylene oxide, propylene oxide, epichlorohydrin,glycidol, glycidyl ethers, especially aryl and alkyl glycidyl ethers, orglycidyl esters, especially the glycidyl esters of tertiary, highlybranched, saturated monocarboxylic acids, which are sold under the tradename Versatic® acids by Deutsche Shell Chemie. Of these, the Versatic®acid glycidyl esters, which are sold under the trade name Cardura® E10,are of very particular advantage and are therefore used with veryparticular preference.

[0121] An example of an advantageous low molecular mass hydrophobicpolyester (C) is the reaction product of malic acid with Cardura® E10.

[0122] Oligomeric hydrophobic polyesters (C) which are advantageous inaccordance with the invention may be prepared in particular by reactingthe diols, triols or tetrols described above in the context of thepolyesters (A1) with the dicarboxylic acids described above in thecontext of the polyesters (A1) and by reacting the resultant polyesters(C) with the above-described epoxides. To prepare the polyesters (C),the polyols are reacted with one another in molar proportions such thatlinear structures result. The skilled worker is therefore able todetermine the appropriate proportions on the basis of his or herexperience or on the basis of simple preliminary tests. In the case ofthe diols, the molar ratio of hydroxyl groups to carboxyl groups isadvantageously 1.0; in the case of the triols it is advantageously atleast 1.5, in particular at least 2.0; and in the case of the tetrols itis advantageously at least 2.0. The reaction may be conducted in stagesor in a one-pot process.

[0123] In accordance with the invention, triols are particularlyadvantageous and are therefore used with particular preference. Oneexample of the particularly advantageous triols is trimethylolpropane,which is used with very particular preference.

[0124] In accordance with the invention, the aliphatic andcycloaliphatic dicarboxylic acids are particularly advantageous and aretherefore used with particular preference. One example of theparticularly advantageous aliphatic dicarboxylic acids is adipic acid;one example of the particularly advantageous cycloaliphatic dicarboxylicacids is hexahydrophthalic acid.

[0125] In place of the dicarboxylic acid it is also possible to use,where they exist, their anhydrides or their transesterification-capablederivatives such as the alkyl esters.

[0126] The amount of polyester (C) in the coating material of theinvention may vary widely and is guided by the requirements of theindividual case. The polyesters (C) are preferably used in an amount,based on the solids of the coating material of the invention, of from 1to 30% by weight.

[0127] The coating material of the invention may comprise at least onearomatic mono- and/or polycarboxylic acid and/or at least one anhydrideof an aromatic polycarboxylic acid (D) in an amount of from 1.5 to 5% byweight, based on the solids of the coating material. Preference is givenin this context to the addition of phthalic anhydride, benzoic acid,and/or alkyl- and/or alkoxy-substituted benzoic acids. With particularpreference, benzoic acid (D) is used.

[0128] The coating material of the invention may further comprise one ormore organic solvents (E). These solvents (E) are usually used inamounts of from 20 to 70% by weight, preferably from 30 to 60% byweight, based in each case on the overall weight of the coatingmaterial.

[0129] Examples of suitable solvents (E) are those described above.

[0130] The coating material of the invention may further comprisesuitable customary coatings additives (F) such as color and/or effectpigments, organic and inorganic, transparent or opaque fillers,nano-particles, heat-curable reactive diluents, reactive diluentscurable with actinic radiation, UV absorbers, light stabilizers,free-radical scavengers, thermally labile free-radical initiators,photoinitiators and photocoinitiators, other, additional binders curablethermally and/or with actinic radiation, additional crosslinking agents,as used in one-component systems, thermal crosslinking catalysts,devolatilizers, slip additives, polymerization inhibitors, defoamers,emulsifiers, wetting agents, dispersants, adhesion promoters, levelingagents, film-forming auxiliaries, sag control agents (SCAs), rheologycontrol additives (thickeners), flame retardants, siccatives, dryers,antiskinning agents, corrosion inhibitors, waxes, flatting agents, orprecursors of organically modified ceramic materials.

[0131] The nature and amount of the additives (F) is guided by theintended use of the coatings produced with the aid of the coatingmaterials of the invention.

[0132] If, for example, a coating material of the invention is used toproduce solid-color topcoats or basecoats, it normally comprises colorand/or effect pigments (F) and, if desired, opaque fillers. Where acoating material of the invention is used, for example, to produceclearcoats or sealers, these additives (F) are naturally not present inthe coating material in question.

[0133] Examples of suitable effect pigments (F) are metal flake pigmentssuch as commercial aluminum bronzes, aluminum bronzes chromated inaccordance with DE 36 36 183 A1, and commercial stainless steel bronzesand also nonmetallic effect pigments, such as pearlescent andinterference pigments, for example. For further details, reference ismade to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998,page 176, “effect pigments” and pages 380 and 381, “Metal oxide-micapigments” to “metal pigments”.

[0134] Examples of suitable inorganic color pigments (F) are naturalpigments such as titanium dioxide, iron oxides, Sicotrans yellow, andcarbon black. Examples of suitable organic color pigments (F) areazomethine pigments, azo pigments, polycyclic pigments, thioindigopigments, and metal complex pigments. For further details, reference ismade to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998,pages 180 and 181, “iron blue pigments” to “black iron oxide”, pages 451to 453 “pigments” to “pigment volume concentration”, page 563,“thioindigo pigments”, page 567, “titanium dioxide pigments”, pages 400and 467, “naturally occurring pigments”, page 459, “polycyclicpigments”, page 52, “azomethine pigments”, “azo pigments”, and page 379,“metal complex pigments”.

[0135] Examples of suitable organic and inorganic fillers (F) are chalk,calcium sulfates, barium sulfate, silicates such as talc or kaolin,silicas, oxides such as aluminum hydroxide or magnesium hydroxide, ororganic fillers such as textile fibers, cellulose fibers, polyethylenefibers, or wood flour. For further details, reference is made to RömppLexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, pages 250 ff.,“fillers”.

[0136] Examples of suitable thermally curable reactive diluents (F) arepositionally isomeric diethyloctanediols or hydroxyl-containinghyperbranched compounds or dendrimers, as described in patentapplication DE 198 09 643 A1, DE 198 40 605 A1 or DE 198 05 421 A1.

[0137] Examples of suitable reactive diluents (F) curable with actinicradiation are those described in Römpp Lexikon Lacke und Druckfarben,Georg Thieme Verlag, Stuttgart, New York, 1998, on page 491 under theheading “reactive diluents”.

[0138] Examples of suitable thermally labile free-radical initiators (F)are organic peroxides, organic azo compounds or C-C-cleaving initiatorssuch as dialkyl peroxides, peroxocarboxylic acids, peroxodicarbonates,peroxide esters, hydroperoxides, ketone peroxides, azo dinitriles, andbenzpinacol silyl ethers.

[0139] Examples of suitable crosslinking catalysts (F) are dibutyltindilaurate, lithium decanoate, bismuth lactate, bismuthdimethylpropioniate, and zinc octoate.

[0140] Examples of suitable photoinitiators and coinitiators (F) aredescribed in Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag,Stuttgart, 1998, pages 444 to 446.

[0141] Examples of suitable additional crosslinking agents (F) are thosecommonly used for thermal curing at temperatures above 90° C., such as

[0142] amino resins, as described for example in Römpp Lexikon Lacke undDruckfarben, Georg Thieme Verlag, 1998, page 29, “amino resins”, in thetextbook “Lackadditive”, [Coatings additives] by Johan Bieleman,Wiley-VCH, Weinheim, New York, 1998, pages 242 ff., in the book “Paints,Coatings and Solvents”, second, completely revised edition, D. Stoye andW. Freitag (eds.), Wiley-VCH, Weinheim, New York, 1998, pages 80 ff., inpatents U.S. Pat. No. 4,710,542 A1 and EP-B-0 245 700 A1, and in thearticle by B. Singh and coworkers, “Carbamylmethylated Melamines, NovelCrosslinkers for the Coatings Industry” in Advanced Organic CoatingsScience and Technology Series, 1991, Volume 13, pages 193 to 207;

[0143] carboxyl-containing compounds or resins, as described for examplein patent DE 196 52 813 A1;

[0144] resins or compounds containing epoxide groups, as described forexample in patents EP 0 299 420 A1, DE 22 14 650 B1, DE 27 49 576 B1,U.S. Pat. No. 4,091,048 A1 and U.S. Pat. No. 3,781,379 A1;

[0145] blocked polyisocyanates, as described for example in patents U.S.Pat. No. 4,444,954 A1, DE 196 17 086 A1, DE 196 31 269 A1, EP 0 004 571A1 and EP 0 582 051 A1; and/or

[0146] tris(alkoxycarbonylamino)triazines, as described in patents U.S.Pat. No. 4,939,213 A1, U.S. Pat. No. 5,084,541 A1, U.S. Pat. No.5,288,865 A1 and EP 0 604 922 A1.

[0147] Examples of suitable devolatilizers (F) are diazadicycloundecaneand benzoin.

[0148] Examples of suitable emulsifiers (F) are nonionic emulsifiers,such as alkoxylated alkanols, polyols, phenols and alkylphenols oranionic emulsifiers such as alkali metal salts or ammonium salts ofalkanecarboxylic acids, alkanesulfonic acids, and sulfo acids ofalkoxylated alkanols, polyols, phenols and alkylphenols.

[0149] Examples of suitable wetting agents (F) are siloxanes, fluorinecompounds, carboxylic monoesters, phosphoric esters, polyacrylic acidsand their copolymers, and polyurethanes.

[0150] An example of a suitable adhesion promoter (F) istricyclodecanedimethanol.

[0151] Examples of suitable film-forming auxiliaries (F) are cellulosederivatives such as cellulose acetobutyrate (CAB).

[0152] Examples of suitable transparent fillers (F) are those based onsilicon dioxide, aluminum oxide or zirconium oxide; for further details,reference is made to Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, Stuttgart, 1998, pages 250 to 252.

[0153] Examples of suitable sag control agents (SCAs) (F) are ureas,modified ureas and/or silicas, as are described, for example, in thereferences EP 0 192 304 A1, DE 23 59 923 A1, DE 18 05 693 A1, WO94/22968, DE 27 51 761 C1, WO 97/12945 and “farbe+lack”, November 1992,pages 829 ff.

[0154] Examples of suitable rheology control additives (F) are thoseknown from patents WO 94/22968, EP 0 276 501 A1, EP 0 249 201 A1 and WO97/12945; crosslinked polymeric microparticles, as disclosed for examplein EP 0 008 127 A1; inorganic phyllosilicates such as aluminum-magnesiumsilicates, sodium-magnesium phyllosilicates andsodium-magnesium-fluorine-lithium phyllosilicates of the montmorillonitetype; silicas such as Aerosils; or synthetic polymers containing ionicand/or associative groups, such as polyvinyl alcohol,poly(meth)acrylamide, poly(meth)acrylic acid, polyvinylpyrrolidone,styrene-maleic anhydride or ethylene maleic anhydride copolymers andtheir derivatives, or hydrophobically modified ethoxylated urethanes orpolyacrylates.

[0155] An example of a suitable flatting agent (F) is magnesiumstearate.

[0156] Examples of suitable precursors (F) for organically modifiedceramic materials are hydrolyzable organometallic compounds, especiallyof silicon and aluminum.

[0157] Further examples of the additives (F) recited above, and examplesof suitable UV absorbers, free-radical scavengers, leveling agents,flame retardants, siccatives, dryers, antiskinning agents, corrosioninhibitors, and waxes (F), are described in detail in the textbook“Lackadditive” by Johan Bieleman, Wiley-VCH, Weinheim, New York, 1998.

[0158] Particularly advantageous coating materials of the inventioncomprise, based in each case on their solids,

[0159] from 15 to 70, preferably from 15 to 45% by weight of the bindercomponent (A),

[0160] from 7 to 50, preferably from 10 to 45% by weight of thecrosslinking component (B),

[0161] from 1 to 30, preferably from 2 to 25% by weight of at least onepolyester (C), and

[0162] from 1.5 to 5, preferably from 2 to 4.5% by weight of at leastone constituent (D),

[0163] the percentages by weight adding up to 100% by weight.

[0164] Where these coating materials of the invention are liquid andhave a viscosity suitable for the application, they may be solvent-free,so-called 100% systems. Preferably, however, the coating materials ofthe invention comprise at least one organic solvent (E) in an amount ofpreferably from 20 to 70, in particular from 30 to 60% by weight, basedin each case on the overall amount of the coating material of theinvention. With particular preference, the organic solvent (E) isemployed in an amount such that the solid-color topcoat, basecoat andclearcoat materials of the invention meet the statutory VOC (volatileorganic compounds) regulations (i.e., VOC<420 g/l).

[0165] The preparation of the coating material of the invention has nospecial features in terms of its method but instead takes place in acustomary and known manner by mixing of the above-described constituentsin appropriate mixing equipment such as stirred vessels, dissolvers,stirred mills, homogenizers, or extruders.

[0166] Where the coating material of the invention also comprisesadditives (F) which may be activated by actinic radiation, it ispreferred to operate in the absence of actinic light in order to preventpremature crosslinking of the coating material.

[0167] The constituents may be employed in any desired sequence. For thecoating material of the invention, however, it is of advantage if it isprepared by the process of the invention.

[0168] In the process of the invention, the binder component (A) and thecrosslinking component (B) are mixed with one another before theapplication of the coating material of the invention. The constituentsdescribed above are employed in amounts so as to give theabove-described proportions or amounts of constituents in the coatingmaterial of the invention.

[0169] In accordance with the invention, the binder component (A) ismixed with at least one of the above-described polyesters (C) before thecrosslinking component (B) is added. This may be done using theapparatus described above, at room temperature or at highertemperatures. In this context it is further of advantage in accordancewith the invention if the above-described aromatic carboxylic acidsand/or their anhydrides (D) are mixed in during this process step. Ingeneral it is advisable here not to exceed a temperature of 180° C.,preferably 150° C. and especially 100° C., in order to prevent thermaldamage to the constituents of the binder component (A).

[0170] In accordance with the invention, it is also of particularadvantage if the above-described polyester(s) (C) is (are) added in theform of a mixing varnish. The composition of the mixing varnishes heremay vary widely. In accordance with the invention it is of veryparticular advantage if the mixing varnish, based on its overall amount,contains from 50 to 90, preferably from 52 to 85, with particularpreference from 54 to 80, with very particular preference from 56 to 75,and in particular from 58 to 70% by weight of at least one polyester (C)and from 10 to 50, preferably from 15 to 48, with particular preferencefrom 20 to 46, with very particular preference from 25 to 44, and inparticular from 30 to 42% by weight of at least one of theabove-described organic solvents (E) and/or at least one of theabove-described additives (F).

[0171] The binder component (A) and the mixing varnish may be mixed withone another in any desired proportions, provided only that theadvantageous proportions described above for the constituents of thecoating material of the invention result. In accordance with theinvention it is advantageous to employ a volume ratio of (A) to mixingvarnish of (3-5):1, preferably (3.5-4.5):1, with particular preference(3.8-4.2):1, and especially 4:1.

[0172] Furthermore, the mixture of binder component (A) and mixingvarnish, on the one hand, and crosslinking component (B), on the otherhand, may be mixed with one another in any desired proportions, providedonly that the advantageous proportions described above for theconstituents of the coating material of the invention result. Inaccordance with the invention it is advantageous to employ a ratio ofmixture to (B) of (3-5):1, preferably (3.5-4.5):1, with particularpreference (3.8-4.2):1 and especially 4:1.

[0173] Not least, the resultant mixture of binder component (A), mixingvarnish and crosslinking component (B), on the one hand, and at leastone organic solvent (E), on the other hand, may be mixed with oneanother in any desired proportions, provided only that the advantageousproportions described above for the constituents of the coating materialof the invention result. In accordance with the invention it isadvantageous to employ a volume ratio of [A)+mixing varnish+(B)] to (E)of (4-7):1, preferably (4.5-6.5):1, with particular preference(4.8-6.2):1 and especially 5:1.

[0174] The resultant, ready-to-apply coating materials of the inventionhave a markedly lower VOC content than the known coating materials ofidentical or comparable composition except for the amount of polyester(C). At the same time, the advantageous profile of properties of theknown coating materials is at least fully retained if not in factexceeded.

[0175] The coating materials of the invention are thereforeoutstandingly suitable for the production of single-coat or multicoatclearcoats or color and/or effect coating systems. Hence they may beused with advantage as interior and exterior architectural coatings, forautomotive OEM finishing, automotive refinishing, the coating ofwindows, doors or furniture, or industrial coating, including containercoating, coil coating and the coating or impregnation of electricalcomponents.

[0176] Suitable coating substrates are all surfaces which are undamagedby curing of the films present thereon using heat alone or incombination with actinic radiation (dual cure). Suitable substratescomprise, for example, metals, plastics, wood, ceramic, stone, textile,fiber composites, leather, glass, glass fibers, glass wool, rock wool,mineral- and resin-bound building materials, such as plasterboard andcement slabs or roof tiles, and also assemblies of these materials.Particularly preferred substrates are the bodies, and parts thereof, ofautomobiles and commercial vehicles.

[0177] The coating material of the invention exhibits very particularadvantages in the context of automotive refinishing and the coating ofcommercial vehicles. The refinish of the invention produced from thecoating material of the invention is particularly notable for itsoutstanding adhesion to the original finish. The solid-color topcoat forcommercial vehicles that is produced from the coating material of theinvention is particularly notable for its masking resistance, its gloss,and its brilliant colors.

[0178] However, the coating materials of the invention also exhibitspecial advantages in the context of automotive OEM finishings. Forinstance, the aqueous basecoat films produced from the customary andknown aqueous basecoat materials may be overcoated without risk ofbleeding with the clearcoat materials of the invention, after which theaqueous basecoat films and the clearcoat films are cured jointly(wet-on-wet technique). The resultant multicoat color and/or effectcoating systems of the invention are notable for very good evenness,brilliant colors, outstanding metallic effects, and very good gloss.

[0179] The coating materials of the invention may be applied by allcustomary application methods, such as spraying, knife coating,brushing, flow coating, dipping, impregnating, trickling, or rolling,for example. The substrate to be coated may per se be at rest, with theapplication equipment or unit being moved. Alternatively, the substrateto be coated, especially a coil, may be moved, with the application unitbeing at rest relative to the substrate or being moved appropriately.Where the coating materials of the invention include constituents whichmay be activated with actinic radiation, application is preferablyconducted in the absence of actinic radiation, especially daylight.

[0180] In general, in automotive OEM finishing and refinishing and inthe coating of commercial vehicles, the coating materials of theinvention are applied in a wet film thickness such that curing thereofgives films having the thicknesses which are advantageous and necessaryfor their functions. In the case of the solid-color topcoat, this filmthickness is from 10 to 150, preferably from 10 to 120, with particularpreference from 10 to 100, and in particular from 10 to 90 μm; in thecase of the basecoat it is from 5 to 50, preferably from 5 to 40, withparticular preference from 5 to 30, and in particular from 10 to 25 μm;and in the case of the clearcoat it is from 10 to 100, preferably from15 to 80, with particular preference from 20 to 70, and in particularfrom 25 to 60 μm. It is, however, also possible to employ the multicoatsystem known from European Patent Application EP 0 817 614 A1,comprising an electrodeposition coat, a first basecoat, a secondbasecoat, and a clearcoat, in which the overall film thickness of thefirst and second basecoats is from 15 to 40 μm and the film thickness ofthe first basecoat is from 20 to 50% of said overall film thickness.

[0181] The applied coating film of the invention is cured thermally, orthermally and with actinic radiation (dual cure).

[0182] The thermal curing has no special features in terms of its methodbut instead takes place in accordance with the customary and knownmethods, such as heating in a forced air oven or irradiation with IRlamps. The thermal curing may also take place in stages.

[0183] Preferably, thermal crosslinking is conducted at temperaturesbelow 100° C. In general it is advisable not to exceed temperatures of90° C., preferably 80° C., and especially 70° C. Preferably, thermalcrosslinking is conducted at room temperature.

[0184] Curing with actinic radiation is preferably conducted with UVradiation and/or electron beams. It is preferred in this case to employa dose of from 1000 to 3000, preferably from 1100 to 2900, withparticular preference from 1200 to 2800, with very particular preferencefrom 1300 to 2700, and in particular from 1400 to 2600 mJ/cm². Ifdesired, this curing may be supplemented with actinic radiation fromother radiation sources. In the case of electron beams, it is preferredto operate under an inert gas atmosphere. This may be ensured, forexample, by supplying carbon dioxide and/or nitrogen directly to thesurface of the coating films. In the case of curing with UV radiation aswell it is possible to operate under inert gas in order to prevent theformation of ozone.

[0185] Curing with actinic radiation is carried out using the customaryand known radiation sources and optical auxiliary measures. Examples ofsuitable radiation sources are flashlamps from the company VISIT,high-pressure or low-pressure mercury vapor lamps, with or without leaddoping in order to open up a radiation window of up to 405 nm, orelectron beam sources. Their arrangement is known in principle and maybe adapted to the circumstances of the workpiece and the processparameters. In the case of workpieces of complex shape, as envisaged forautomobile bodies, the areas not accessible to direct radiation (shadowregions) such as cavities, folds and other structural undercuts may be(partly) cured using point, all-round or small-area emitters inconjunction with an automatic movement apparatus for the irradiation ofcavities or edges.

[0186] The equipment and conditions for these curing methods aredescribed, for example, in R. Holmes, U.V. and E.B. Curing Formulationsfor Printing Inks, Coatings and Paints, SITA Technology, Academic Press,London, United Kingdom 1984.

[0187] Curing may take place in stages, i.e., by multiple exposure tolight or actinic radiation. It may also be carried out alternately,i.e., by curing with UV radiation and electron beams in alternation.

[0188] Where thermal curing and curing with actinic radiation areemployed together, these methods may be used simultaneously oralternately. Where the two curing methods are used alternately, it ispossible, for example, to begin with thermal curing and end with actinicradiation curing. In other cases it may prove advantageous to begin withactinic radiation curing and to end with it. Particular advantagesresult if the coating films are cured in two separate process steps,first with actinic radiation and then thermally.

[0189] On application and curing, as well, the coating materials of theinvention, at significantly lower VOC contents, exhibit the sameoutstanding profile of properties as the known coating materialscontaining no polyesters (C) but otherwise of identical or comparablematerial composition.

EXAMPLES Preparation Example 1

[0190] The Preparation of a Hydroxyl-Containing Polyester (A1)

[0191] A 4 liter polycondensation vessel with stirrer, steam-heatedcolumn and water separator was charged with 796 parts by weight oftrimethylolpropane, 540 parts by weight of isononanoic acid, 821 partsby weight of phthalic anhydride and 83 parts by weight of xylene andthis initial charge was slowly heated. Condensation was carried out at atemperature of max. 190° C. to an acid number of 5 mg KOH/g and aviscosity of 8.0 dPas (60% strength in xylene). The mixture wassubsequently cooled, diluted at 130° C. with 910 parts by weight ofShellsol® A and cooled further to room temperature.

[0192] The resulting polyester had a solids content of 66.5%, an acidnumber of 5 mg KOH/g, an OH number of 97 mg KOH/g, and a viscosity of 70dPas (original).

Preparation Example 2

[0193] The Preparation of a (meth)acrylate copolymer (A2)

[0194] A stainless steel reactor of capacity 4 liters, equipped withstirrer, reflux condenser, an initiator feed and a monomer feed, wascharged with 700 parts by weight of the polyester (A1) from PreparationExample 1 and 70 parts by weight of VEOVA® 10 (vinyl ester of Versatic®acid) and this initial charge was heated to 165° C. A monomer mixture of350 parts by weight of styrene, 155 parts by weight of butanediolmonoacrylate and 125 parts by weight of methyl methacrylate was addeduniformly with stirring to the initial charge over the course of fourhours, as was an initiator solution of 14 parts by weight ofdi-tert-butyl peroxide, 44 parts by weight of Shellsol®A and 25 parts byweight of xylene over the course of five hours. The feed streams werecommenced simultaneously. Following the addition, the reaction mixturewas postpolymerized for two hours. The temperature was subsequentlylowered to 120° C. and the resulting (meth)acrylate copolymer (A2) wasdiluted with butyl acetate to a solids content of 65% by weight andadmixed with 5 parts by weight of benzoic acid.

[0195] The (meth)acrylate copolymer (A2) had a solids content of 65% byweight, an acid number of 5.3 mg KOH/g, a viscosity of 2.3 dPas (55%strength in butyl acetate), and a hydroxyl number of 90 mg KOH/g.

Preparation Example 3

[0196] The Preparation of a Polyester (C) for Use in Accordance with theInvention

[0197] 284.4 parts by weight of hexahydrophthalic anhydride and 98.3parts by weight of trimethylolpropane were weighed out into a steelreactor and heated to 150° C. Subsequently, 458.5 parts by weight ofVersatic® acid glycidyl ester (Cardura® E 10) were metered in at auniform rate over the course of one hour. The reaction mixture was heldat 150° C. until an acid number of 4 mg KOH/g was reached. The resultingpolyester was adjusted with butyl acetate at 110° C. to a solids contentof 81% by weight. The viscosity of the diluted product was 40 dpas.

Preparation Example 4

[0198] The Preparation of a Mixing Varnish for Use in Accordance withthe Invention

[0199] The mixing varnish for use in accordance with the invention wasprepared from 82.7 parts by weight of the polyester (C) from PreparationExample 3, 3 parts by weight of a 2% strength solution of dibutyltindilaurate, 2.3 parts by weight of a commercial light stabilizer (HALSfrom Ciba Specialty Chemicals), 0.7 part by weight of a commercialleveling agent (polyether-modified polydimethylsiloxane from Byk), 5parts by weight of a further commercial leveling agent (acrylatecopolymer from Byk) and 6 parts by weight of organic solvents (mixtureof butyl acetate and methyl isobutyl ketone).

Preparation Example 5

[0200] The Preparation of a Crosslinking Component (B) for Use inAccordance with the Invention

[0201] The crosslinking component (B) was prepared from the followingconstituents:

[0202] 88.6 parts by weight of Desmodur® N 3600¹)

[0203] 5.7 parts by weight of butyl acetate 98/100 and

[0204] 5.7 parts by weight of methyl isobutyl ketone.

Preparation Example 6

[0205] The Preparation of a Solvent Mixture (E) for Adjusting theViscosity for Application

[0206] The solvent mixture (E) was prepared from the following solvents:Xylene 15.0 parts by weight Solventnaphta ® 13.0 parts by weightPetroleum spirit 135/180 10.0 parts by weight Butyl glycol acetate  3.0parts by weight n-Butyl acetate 98/100 50.0 parts by weight1-Methoxypropyl 2-acetate  5.0 parts by weight Butoxyl  2.0 parts byweight Dipentenes  2.0 parts by weight

EXAMPLE

[0207] The Preparation of a Clearcoat Material of the Invention and of aClearcoat of the Invention for Automotive OEM Finishing or Refinishing

[0208] To prepare the clearcoat material of the invention, the(meth)acrylate copolymer (A2) from Preparation Example 2 and the mixingvarnish from Preparation Example 4 were mixed with one another in avolume ratio of (A2) to mixing varnish of 4:1.

[0209] The resulting mixture was mixed in turn with the crosslinkingcomponent (B) from Preparation Example 5 and the solvent mixture (E)from Preparation Example 6 in a volume ratio of mixture to (B) to (E) of4:1:1, to give the ready-to-apply clearcoat material of the invention.It had a VOC of less than 420 g/l, which was therefore below the limitprescribed by statute.

[0210] The clearcoat material was applied in two spray passes with aflash-off time of 15 minutes in between to steel panels which had beencoated with a surfacer coat produced from a commercial conventionalsurfacer (commercial product Glasurit Grundfüller [primer-surfacer]283-1874 from Glasurit GmbH, Münster, Germany) based on a bindercontaining epoxide groups and on an amino-functional curing agent, andwith a black basecoat produced from a commercial black basecoat materialfrom BASF Coatings AG. The clearcoat film was subsequently dried at 20°C. for 16 h. The dry film thickness was from 50 to 60 μm.

[0211] The clearcoat of the invention was outstandingly even and freefrom surface defects. It showed outstanding adhesion to the basecoat,and this adhesion was essentially retained even after exposure in aconstant condensation climate. It was scratch resistant and stable toweathering and to chemicals. Furthermore, it was masking resistant inthe sense of the masking test described in Examples 1 to 6 ofInternational Patent Application WO 96/26969.

What is claimed is:
 1. A nonaqueous coating material curable thermallyor thermally and with actinic radiation, comprising (A) ahydroxyl-containing binder component comprising (A1) at least onehydroxyl-containing polyester and (A2) at least one hydroxyl-containing(meth)acrylate copolymer prepared at least partly in the presence of thepolyester (A1), (B) at least one crosslinking component comprising atleast one polyisocyanate, and (C) at least one low molecular mass and/oroligomeric, essentially unbranched, hydrophobic polyester having atleast two hydroxyl groups in the molecule, an OH number of from 56 to500 mg KOH/g, an acid number <10 mg KOH/g, and a number-averagemolecular weight Mn of from 300 to 2000 daltons.
 2. The coating materialas claimed in claim 1, wherein the binder component, based on itsoverall amount, contains from 20 to 60% by weight of the polyesters (A1)and from 40 to 80% by weight of the (meth)acrylate copolymers (A2). 3.The coating material as claimed in claim 1 or 2, comprising at least onearomatic mono- and/or polycarboxylic acid and/or at least one anhydrideof an aromatic polycarboxylic acid (D).
 4. The coating material asclaimed in any of claims 1 to 3, wherein the polyester (C) has thegeneral formula I [R¹—CH(OH)—CH₂—OOC—]₂R  (I) where R=substituted orunsubstituted divalent C₁ to C₂₀ alkanediyl, C₂ to C₂₀ alkenediyl, C₄ toC₂₀ cycloalkanediyl or cycloalkenediyl, C₆ to C₁₂ arylidene or divalentC₆ to C₂₀ arylalkyl, arylalkenyl, arylcycloalkyl or arylcycloalkenylradical; or substituted or unsubstituted divalent aliphatic,cycloaliphatic, acyclic or cyclic olefinically unsaturated, aromatic,aliphatic-aromatic, cycloaliphatic-aromatic, acyclic unsaturatedaromatic or cyclic unsaturated aromatic radical containing at least onecarboxylic ester group; R¹=hydrogen atom or monovalent substituted orunsubstituted C₁ to C₂₀ alkyl, C₂ to C₂₀ alkenyl, C₄ to C₁₂ cycloalkylor cycloalkenyl, C₆ to C₁₂ aryl or C₆ to C₂₀ arylalkyl, arylalkenyl,arylcycloalkyl, arylcycloalkenyl, alkylaryl, alkenylaryl,cycloalkylaryl, cycloalkenylaryl, alkylcycloalkyl, alkylcycloalkenyl,alkenylcycloalkyl, alkenylcycloalkenyl, cycloalkylalkyl,cycloalkenylalkyl, cycloalkylalkenyl or cycloalkenylalkenyl radical. 5.The coating material as claimed in claim 4, wherein the radical Rcontains at least one hydroxyl group.
 6. The coating material as claimedin claim 4 or 5, wherein the radical R¹ is substituted, in particular byat least one of the following substituents: —F, —Cl, —Br, —I, —CN, —NO₂,—OH, —OR², —SH, —SR², —NH₂, —NHR², —N(NR²)₂ and/or —OOC—R², where R² isas defined for R¹ with the exception of the hydrogen atom.
 7. Thecoating material as claimed in any of claims 4 to 6, wherein the radicalR¹ is a monosubstituted methyl group, especially a methyl groupmonosubstituted by —OOC—R² where the radical R² denotes in particular abranched C₄ to C₁₂ alkyl radical.
 8. The coating material as claimed inany of claims 1 to 7, wherein the polyester (C) is present in an amountof from 1 to 30% by weight, based on the solids of the coating material.9. The coating material as claimed in any of claims 1 to 8, comprising,based on its solids, from 15 to 70% by weight of the binder component(A), from 7 to 50% by weight of the crosslinking component (B), from 1to 30% by weight of at least one polyester (C), and from 1.5 to 5% byweight of at least one constituent (D), the percentages by weight addingup to 100% by weight.
 10. The coating material as claimed in any ofclaims 1 to 9, comprising based on its overall amount from 20 to 70% byweight of at least one organic solvent (E).
 11. A process for preparingthe coating material as claimed in any of claims 1 to 10, in which thebinder component (A) and the crosslinking component (B) are mixed withone another prior to application, which comprises adding to the bindercomponent (A), prior to mixing, at least one low molecular mass and/oroligomeric, essentially unbranched, hydrophobic polyester containing atleast two hydroxyl groups in the molecule and having an OH number offrom 56 to 500 mg KOH/g, an acid number <10 mg KOH/g and anumber-average molecular weight Mn of from 300 to 2000 daltons.
 12. Theprocess as claimed in claim 11, wherein the polyester (C) has thegeneral formula I [R¹—CH(OH)—CH₂—OOC—]₂R  (I) where R=substituted orunsubstituted divalent C₁ to C₂₀ alkanediyl, C₂ to C₂₀ alkenediyl, C₄ toC₂₀ cycloalkanediyl or cycloalkenediyl, C₆ to C₁₂ arylidene or divalentC₆ to C₂₀ aralalkyl, arylalkenyl, arylcycloalkyl or arylcycloalkenylradical; or substituted or unsubstituted divalent aliphatic,cycloaliphatic, acyclic or cyclic olefinically unsaturated, aromatic,aliphatic-aromatic, cycloaliphatic-aromatic, acyclic unsaturatedaromatic or cyclic unsaturated aromatic radical containing at least onecarboxylic ester group; R¹=hydrogen atom or monovalent substituted orunsubstituted C₁ to C₂₀ alkyl, C₂ to C₂₀ alkenyl, C₄ to C₁₂ cycloalkylor cycloalkenyl, C₆ to C₁₂ aryl or C₆ to C₂₀ arylalkyl, arylalkenyl,arylcycloalkyl, arylcycloalkenyl, alkylaryl, alkenylaryl,cycloalkylaryl, cycloalkenylaryl, alkylcycloalkyl, alkylcycloalkenyl,alkenylcycloalkyl, alkenylcycloalkenyl, cycloalkylalkyl,cycloalkenylalkyl, cycloalkylalkenyl or cycloalkenylalkenyl radical. 13.The process as claimed in claim 12, wherein the radical R contains atleast one hydroxyl group.
 14. The process as claimed in claim 12 or 13,wherein the radical R¹ is substituted, in particular by at least one ofthe following substituents: —F, —Cl, —Br, —I, —CN, —NO₂, —OH, —OR², —SH,—SR², —NH₂, —NHR², —N(NR²)₂ and/or —OOC—R², where R² is as defined forR¹ with the exception of the hydrogen atom.
 15. The process as claimedin any of claims 12 to 14, wherein the radical R¹ is a monosubstitutedmethyl group, especially a methyl group monosubstituted by —OOC—R² wherethe radical R² denotes in particular a branched C₄ to C₁₂ alkyl radical.16. The process as claimed in any of claims 11 to 15, wherein thepolyester (C) is added in the form of a mixing varnish containing, basedon the mixing varnish, from 50 to 90% by weight of at least onepolyester (C) and from 10 to 50% by weight of at least one organicsolvent (E) and/or of a customary coatings additive (F).
 17. The processas claimed in claim 16, wherein the binder component (A) and the mixingvarnish are mixed with one another in a volume ratio of (A) to mixingvarnish of (3-5):1.
 18. The process as claimed in claim 17, wherein themixture of binder component (A) and mixing varnish and the crosslinkingcomponent (B) are mixed with one another in a volume ratio of mixture to(B) of (3-5):1.
 19. The process as claimed in claim 18, wherein themixture of binder component (A), mixing varnish and crosslinkingcomponent (B) with at least one organic solvent (E) is mixed together ina volume ratio of [(A)+mixing varnish+(B)] to (E) of (4-7):1.
 20. Theuse of the coating material as claimed in any of claims 1 to 10 and/orof the coating material prepared by the process as claimed in any ofclaims 11 to 19 to produce single-coat or multicoat clearcoats and/orcolor and/or effect coating systems.
 21. The use as claimed in claim 20,wherein the coating material is used as an interior and exteriorarchitectural coating, for automotive OEM finishing, automotiverefinishing, the coating of commercial vehicles, the coating of windows,doors or furniture or industrial coating, including container coating,coil coating and the coating or impregnation of electrical components.